Descent with Modification, Cellular Replication, and Evolutionary Fitness

Vocabulary flashcards covering topics on descent with modification, evolutionary fitness, natural selection, cell division, and chromosome concepts.

Descent with Modification

The unifying principle in biology co-announced by Charles Darwin and A. R. Wallace in 1858, which explains patterns of shared ancestry among organisms over time.

Phenotype

An organism's whole body characteristics and measurable physical or behavioral traits.

Evolution (Definition #1)

The change in the average value in a population of a genetically based characteristic over time.

Natural Selection

An evolutionary force that explains the match between organisms' traits and their local environment based on differential reproductive success, variation, and inheritance.

Four Forces of Evolution

The four fundamental processes that cause evolutionary change: natural selection, mutation, gene flow, and genetic drift.

Evolutionary Fitness

The total number of offspring produced by an individual over the course of its lifetime.

Relative Fitness

A measure of reproductive capability where traits do not need to be perfect, but rather 'good enough' relative to other individuals in a given environment.

Herbert Spencer

The philosopher who coined the phrase 'survival of the fittest', which is recognized as somewhat circular given the biological definition of fitness.

Binary Fission

The mode of asexual cell replication used by prokaryotes, such as bacteria, to divide into identical daughter cells.

Mitosis

The process of cell replication in eukaryotic organisms used for reproduction in single-celled eukaryotes (e.g., euglenids) and for growth and repair in multicellular organisms.

Cell Division Sequence

The chronological progression of cell division through Interphase (where chromosomes are duplicated), Prophase, Metaphase, Anaphase (where sister chromatids separate), Telophase, and Cytokinesis.

Homologous Chromosomes

A pair of chromosomes in a diploid organism that carry the same genes, with one inherited from each parent.

Sister Chromatids

Two identical joined copies of a single replicated chromosome that are separated during anaphase.

Ploidy

The number of complete sets of chromosomes in a cell.

Haploid

Describing a cell or organism containing a single set of unpaired chromosomes, represented mathematically as $n$.

Diploid

Describing a cell or organism containing two homologous sets of chromosomes, represented mathematically as $2n$.

Human Karyotype Formula

The chromosome count formula for human somatic cells containing $23$ pairs of chromosomes, written as $2n = 46$.

Rule of Thumb for an Individual

The criteria proposed by Folse III et al. (2010) defining an individual organism as 'one genome in one body'.

Multicellularity

The organizational state of an individual composed of multiple genomically identical cells, providing evolutionary advantages in varied environments.

Unicellularity

The state of being an organism comprised of a single cell that carries out all biological functions.